Lubricating oil viscosity index improvers have been widely used by the industry. Typically, these viscosity index improvers comprise a long chain hydrocarbon polymer. Ethylene-propylene copolymers and terpolymers have been widely used as the polymers of choice.
High molecular weight ethylene-propylene polymers and ethylene-propylene-diene terpolymers, having viscosity average molecular weights of from about 20,000 to 300,000, are generally produced employing Ziegler catalysts, generally VCl.sub.4 or VOCl.sub.3 with a halide source, such as organoaluminum halides and/or hydrogen halides. Such high molecular weight EP and EPDM polymers find use as viscosity index improvers. See, e.g., U.S. Pat. Nos. 3,563,964; 3,697,429; 4,306,041; 4,540,753; 4,575,574; and 4,666,619.
The following disclosures include disclosures of EP/EPDM polymers of M.sub.n of 700/500,000, also prepared by conventional Ziegler catalysts.
In accordance with the instant invention there are provided oleaginous compositions, particularly lubricating oil compositions, exhibiting improved viscosity index containing an additive comprised of a particular type of ethylene alpha-olefin polymer. This ethylene alpha-olefin polymer has vinylidene-type terminal unsaturation.
U.S. Pat. No. 4,668,834 to Uniroyal Chemical discloses preparation (via certain metallocene and alumoxane catalyst systems) and composition of ethylene-alpha olefin copolymers and terpolymers having vinylidene-type terminal unsaturation, which are disclosed to be useful as intermediates in epoxy-grafted encapsulation compositions.
Japanese Published Patent Application 87-129,303A of Mitsui Petrochemical relates to narrow molecular weight distribution (M.sub.w /M.sub.n &lt;2.5) ethylene alpha-olefin copolymers containing 85-99 mol % ethylene, which are disclosed to be used for dispersing agents, modifiers or materials to produce toners. The copolymers (having crystallinity of from 5-85%) are prepared in the presence of a catalyst system comprising Zr compounds having at least one cycloalkadienyl group and alumoxane.
European Patent 128,046 discloses (co)polyolefin reactor blends of polyethylene and ethylene higher alpha-olefin copolymers prepared by employing described dual-metallocene/alumoxane catalyst systems.
European Patent Publication 129,368 discloses metallocene/alumoxane catalysts useful for the preparation of ethylene homopolymer and ethylene higher alpha-olefin copolymers.
European Patent Application Publication 257,696 A1 relates to a process for dimerizing alpha-olefins using a catalyst comprising certain metallocene/alumoxane systems.
PCT Published Patent Application WO 88/01626 relates to transition metal compound/alumoxane catalysts for polymerizing alpha-olefins.